<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
</head>
<body>
  
</body>
<script>
  let result = 100 + true + 21.2 + null + undefined + "Tencent" + [] + null + 9 +false;
  console.log(result)//NaNTencentnull9false

  console.log([] == false);
  //true  都转换为数字，false--0, []--" "--0
  console.log(![] == false);
  //true   false == false

  async function timeout(){
    return "hello world"
  }
  timeout().then( res => {
    console.log(res)
  })

  //数字string转换为number
  let str = "5"//string
  let str1 = str*1//number


</script>
</html>